<?php

$a = 90+90;

$a +=20; //$a = $a+20;

$b = $a++;

var_dump($a,$b);

$str = "xue"."bi"."ng";

$str .= 89;//$str = $str.89;

var_dump($str);

$num = 60;

var_dump(!($num>=80 and $num<90));

$num1= 90;
$num2 = 100;

$num3 = $num1>$num2 ? $num1 : $num2;

var_dump($num3);